The Stanford ACE will support an integrated basic and clinical research program focused on tolerance induction and immune modulation to prevent or treat autoimmune disease. The major theme of the Stanford Autoimmunity Center of Excellence (the Center) is the study of the regulation of CD4 T cells in pathogenesis and treatment of autoimmune diseases. The Center will support and be supported by other ACE groups across the United States; and will take advantage of Stanford's documented leadership in basic and clinical research, technology development, and education in clinical immunology. Success of the Center will be supported by the interrelationships previously established at Stanford among clinician scientists from multiple departments studying autoimmune diseases in multiple organs and tissues. The Stanford ACE will be composed of outstanding basic and clinical investigators from multiple disciplines at Stanford Medical School and proposes both a basic Research Project, centered on CD4 T cell unresponsiveness, and a translational Research Project to study a new T cell lineage (termed Th17 cells) that is characterized by the ability of these lymphocytes to secrete high levels of the proinflammatory cytokine interleukin-17 (IL-17). Proposed clinical research projects encompass three different autoimmune diseases [diffuse systemic sclerosis (SSc), psoriatic arthritis and systemic juvenile idiopathic arthritis (SJIA)] that afflict adults and children, as well as organ systems including joints, skin, blood elements, and blood vessels, and will both test efficacy of therapy and develop tests to characterize the mechanisms of action of these therapeutics. The proposed Pilot and Feasibility Project proposes a two year research plan in Systemic Juvenile Idiopathic Arthritis (SJIA) patients to identify and validate urine peptide biomarkers that predict (a) response to TNF inhibition; (b) response to IL-1 inhibition; and (c) impending disease flare. In addition, this proposal will provide other ACE groups access to cutting edge reagents and technology platforms for studying human autoimmune diseases, and dissemination of Educational Materials that can be used by other ACEs to teach clinical immunology concepts to high school, undergraduate, graduate, postgraduate, and clinical fellows and faculty. The Stanford ACE proposes to support integrated basic, pre-clinical and clinical research by proposing and then conducting basic and translational research into the mechanism of CD4 T cell unresponsiveness; two clinical trials that include novel therapies and mechanistic studies of these therapies for autoimmune diseases; and a pilot proposal that intends to develop new bi omarkers of disease. PROJECT 1A: Clinical Component (Genovese, M) CLINICAL COMPONENT DESCRIPTION (provided by applicant): Stanford University Medical Center (SUMC) has an extraordinary tradition of medical, translational, and basic science research. An outstanding array of resources, faculty, and facilities will be available to support the proposed ACE site at Stanford University. This proposal brings together a skilled group of translational researchers with a track record of productivity in both laboratory and clinical research focusing on human autoimmune mediated diseases. Stanford has brought together various disciplines to demonstrate both accomplishment and ability to work together with the following fields represented: Adult Rheumatology, Dermatology, Pulmonary Medicine, and Pediatric Rheumatology. The projects chosen for this submission highlight the significant collaborations that exist between Rheumatology (Adult and Pediatric), Dermatology and Pulmonary Medicine. Both clinical trials projects explore dermatologic and rheumatologic manifestations of diseases such as Psoriatic arthritis and Systemic Sclerosis. Clinical Trial Concept 1: The use of an anti- IL-17 mab in the treatment of active Psoriatic Arthritis Primary Hypothesis: The proportion of patients achieving the ACR 20 response from Baseline to Week 14 among active Psoriatic Arthritis (PSA) subjects treated with IL-17 mab is larger than the proportion achieving ACR 20 response from Baseline to Week 14 among active PSA subjects treated with placebo Objectives: The goal of this study is to determine the safety and efficacy of a monoclonal antibody to lnterleukin-17 (IL-17 mab) in the treatment of PsA with active skin and joint disease. Clinical Trial Concept 2: The use of CTLA-4lg (abatacept) in subjects with diffuse systemic sclerosis Primary hypothesis: Given several lines of evidence supporting the role of activated T cells in affected skin, we hypothesize that inhibiting T cell activation may lead to significant clinical improvement in skin manifestations in patients with diffuse systemic sclerosis (dSSc), and that changes in tissue and blood autoantibody and cytokine profiles will be associated with clinical response. Objectives: The primary goal of this study is to determine the safety and efficacy of CTLA-4lg (Abatacept) for the treatment of cutaneous manifestations of dSSc RELEVANCE (See instructions): The Stanford ACE will support an integrated basic and clinical research program focused on tolerance induction and immune modulation to prevent or treat autoimmune (Al) disease. The Stanford ACE proposes clinical research projects that encompass three different autoimmune diseases (SSc, psoriatic arthritis and SJIA), and proposes to study the MoA of therapeutics for preventing or treating different Al diseases.